John Carmack's Fast Inverse Square Root: https://en.wikipedia.org/wiki/Fast_inverse_square_root#Overv.... The first time I really and truly felt that people approach problems differently from how I, by default, go about them.
"// what the fuck? "
You'd be hard pressed to write an inverse square cube without basically rewriting the whole function. There's nothing that can be reused. The only saving grace is that it is side-effect free, so replacement is trivial, unlike a lot of other code that's not maintainable.
You mean inverse cube root? I believe the geometry ain’t easily upgradeable this way.
As the designer of the code, you would understand that the inverse square root is a standalone problem.